1. Field of the Invention
The present invention relates to a method for inhibiting tumor growth, in particular to the method for inhibiting the growth of leukemia cell or pancreatic cancer cell by a compound extracted and purified from Antrodia cinnamomea. 
2. The Prior Arts
Antrodia cinnamomea is a perennial mushroom belonging to the order Aphyllophorales and the family Polyporaceae, which is also known as Niu Chang-Zhi, Chang-Ku, Red-Chang, Red Chang-Zhi and the like. It is an endemic medicinal mushroom in Taiwan growing on the inner rotten heart wood wall of the only host, Cinnamomum kanehirae, The extremely slow growth of fruiting bodies of Antrodia cinnamomea and the rarely distributed natural Cinnamomum kanehirae make the wild Antrodia cinnamomea be difficult to get and expensive. In traditional Taiwanese medicine, Antrodia cinnamomea is commonly used in detoxification, especially effective in treatment food poisoning and drug poisoning. It has a long folk history in treating hepatic viral infection and liver diseases.
Antrodia cinnamomea has many complicated compounds as general edible and medicinal mushrooms, and many of them have been proved to have pharmacological and biological activities. Among them, fermented Antrodia cinnamomea extract and adenosine isolated from Antrodia cinnamomea prevented serum deprivation-induced PC12 cell apoptosis through suppression of JNK and p38 activities and activation of adenosine A receptors, respectively. (Lu, M. K., Cheng, J. J., Lai, W. L., Lin, Y. J., and Huang, N. K. 2008. Fermented Antrodia cinnamomea extract protects rat PC12 cells from serum deprivation-induced apoptosis: the role of the MAPK family. J. Agric. Food Chem., 56(3): 865-874; Lu, M. K., Cheng, J. J., Lai, W. L., Lin, Y. R., and Huang, N. K. 2006. Adenosine as an active component of Antrodia cinnamomea that prevents rat PC12 cells from serum deprivation-induced apoptosis through the activation of adenosine A(2A) receptors. Life Sci., 79(3): 252-258). Ethyl acetate extracted from fruiting bodies of Antrodia cinnamomea attenuated the invasion of hepatic cancer cells PLC/PRF/5PLC/PRF/5, and the mechanism is related to the inhibition of nuclear factor kappa B activity. (Hsu, Y. L., Kuo, P. L., Cho, C. Y., Ni, W. C., Tzeng, T. F., Ng, L. T., Kuo, Y. H., & Lin, C. C. 2007. Antrodia cinnamomea fruiting bodies extract suppresses the invasive potential of human liver cancer cell line PLC/PRF/5 through inhibition of nuclear factor kappa B pathway. Food Chem. Toxicol., 45(7): 1249-1257). Polysaccharides isolated from Antrodia cinnamomea inhibited cyclin D1 expression through inhibition of vascular endothelial growth factor (VEGF) receptor signal transduction and suppressed angiogenesis (Cheng, J. J., Huang, N. K., Chang, T. T., Wang, D. L., & Lu, M. K. 2005. Study for anti-angiogenic activities of polysaccharides isolated from Antrodia cinnamomea in endothelial cells. Life Sci., 76(26): 3029-3042).
Leukemia, one of hematological malignancies, is the most frequently occurring malignancy diagnosed in children, representing nearly 40% of cancer cases. The main reason for the high incidence is the rapid proliferation of immature blood affected by factors including gene, viral infection, drugs, and the like. The problems of serious side effects and high recurrence rate from leukemia treatment have made complete remission difficult though many progresses in clinical therapy have been made. The majority of pancreatic cancers are adenocarcinomas of the lining epithelium in the pancreatic ducts. It is seldom detected in its early stages because of its retroperitoneal position and no distinct symptoms. There is still no ideal treatment for pancreatic cancer due to the high incidence of recurrence and metastasis, as well as resistance to conventional chemotherapy and radiotherapy. The 5-year survival rate is less than 5% in the non-resectable patients, which makes pancreatic cancer a leading cause of cancer death. Both of the leukemia and pancreatic cancer have a low remission rate, therefore development of novel drugs for cancer treatment with little side effect is of urgent need at present.
Though Antrodia cinnamomea extracts were reported to have pharmaceutical effects from many studies, the application in growth inhibition of leukemia and pancreatic cancer cell was never reported so far. Searches for exact active ingredients in antitumor effect are still in the experimental stage, and are remained to be elucidated. Further experiments are needed to identify the effective composition for inhibition of tumor growth since the components of Antrodia cinnamomea were analyzed in succession. It will be of great beneficial in therapy of leukemia and pancreatic cancer if the tumor inhibiting components from Antrodia cinnamomea extracts are found and they can be applied in inhibition of leukemia and pancreatic cancer cell growth.